The present invention relates to a hydraulic circuit, and more particularly, to a circuit for extending and retracting a telescoping service line and for independently operating an extendible support boom. During the course of producing fluids from a petroleum well it is often desirable or necessary to subject the well to a treatment procedure in order to stimulate its fluid production. This procedure usually involves the injection of fluids under high pressure, such as 20,000 psi, to fracture the producing earth formations, or the injection of an acid solution to dissolve or otherwise remove flow of obstructing material, thereby increasing the flow of petroleum from the formation into the well. In order to carry out these well stimulating procedures, it is commonplace to employ an articulated pipe assembly, called a service line, to conduct the fluid from a pump system to the wellhead. Such a service line usually comprises a plurality of straight lengths of rigid pipe interconnected end-to-end by pipe swivel joints so the service line can be extended and retracted for use in treatment of the well.
It is known to employ the articulated well service pipe line mounted on a mobile telescoping boom assembly. This articulated pipe line may include a relatively large number of fairly short sections of pipe interconnected by a plurality of pipe elbows and swivel joints that extend from and retract into their rest or stowed position in an accordion-like manner. The telescoping boom assembly is first extended to its desired length and then the supported articulated pipe line is moved from its folded position toward its extended position until the outer end of the pipe line reaches the wellhead.